Author Topic: 2007Saab 9-3 TiD - Problems starting when hot  (Read 143 times)

malc.savvy

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2007Saab 9-3 TiD - Problems starting when hot
« on: 17 September 2022, 05:53:47 PM »
Please is their one out their that can help me?
I have been on a few Saab Forums I tried different things of what they said but to no avail. I have a Saab 93 diesel estate 07 will not start if the engine is hot or the weather outside is hot? Anything above 17 degrees it will not start.
Starts great in the cold weather not a problem I replaced ECU & ECM no difference.
I have had 2 diagnostic tests on it when the car is working and when it not & did not come up with any bad codes by two AA mechanics & also by two independent garages. They used a Tech II
But someone said it could be the Crankshaft Sensor? I looked have different seniorís & Fuses. But no joy. If anybody could help it would be so appreciated, Thankyou.

sgould

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Re: 2007Saab 9-3 TiD - Problems starting when hot
« Reply #1 on: 17 September 2022, 06:38:51 PM »
Welcome! :í

I havenít any hands on experience with the modern diesels, but the hot start problem in a petrol Saab is almost always the crankshaft position sensor.. The only check that you can do on a CPS is to check the resistance.  On the Diesel engine is should be 860 ohms, but this varies a bit with temperature.

On the petrol the allowable resistance is 770 - 950 ohms. So it must be similar to the petrol one.   There are 3 pins in the connector.  Onli two should show a resistance across them.  The third pin is a connection to the screen in the cable.

 Unfortunately, since the resistance varies with temperature and the engine can get quite hot, itís not always possible to do the check with 100% certainty, but if itís quite high, it could be a sign of failure as they seem to fail with the resistance increasing.

The other pointer to the CPS being at fault is that the engine management will not wake up and store failure codes if it gets no signal from the CPS.  So tha fact you have no codes, could point  to the CPS as well.

The only certain check is to replace the CPS and try it.
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malc.savvy

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Re: 2007Saab 9-3 TiD - Problems starting when hot
« Reply #2 on: 17 September 2022, 07:46:17 PM »
Just changed the CPS today but no difference. But thanks for the quick reply. Cheers Malc

sgould

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Re: 2007Saab 9-3 TiD - Problems starting when hot
« Reply #3 on: 17 September 2022, 10:49:07 PM »
There's also a camshaft sensor on a diesel, but i have no info about that, sorry!
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malc.savvy

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Re: 2007Saab 9-3 TiD - Problems starting when hot
« Reply #4 on: 19 September 2022, 04:06:57 PM »
Yes people have said this in the past but it seems very unlikely, but yes again thank you.
keep racking your brains for me. Cheers Malc.